Polymers containing oxygen and sulfur alicyclic units and photoresist compositions comprising same

ABSTRACT

The invention includes polymers that contain a heterocyclic ring, preferably an oxygen-or sulfur-containing ring. The heterocyclic ring is preferably fused to the polymer backbone. The invention also provides photoresists that contain such polymers, particularly for imaging at short wavelengths such as sub-200 nm.

This application is a continuation of application Ser. No. 09/567,634,filed May 9, 2000, now U.S. Pat. No. 6,306,554.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to new polymers that contain oxygen and/orsulfur alicyclic (heteroalicyclic) units and use of such polymers as aresin binder component for photoresist compositions, particularlychemically-amplified positive-acting resists that can be effectivelyimaged at short wavelengths such as sub-200 nm, particularly 193 nm.

2. Background

Photoresists are photosensitive films used for transfer of images to asubstrate. A coating layer of a photoresist is formed on a substrate andthe photoresist layer is then exposed through a photomask to a source ofactivating radiation. The photomask has areas that are opaque toactivating radiation and other areas that are transparent to activatingradiation. Exposure to activating radiation provides a photoinducedchemical transformation of the photoresist coating to thereby transferthe pattern of the photomask to the photoresist-coated substrate.Following exposure, the photoresist is developed to provide a reliefimage that permits selective processing of a substrate.

A photoresist can be either positive-acting or negative-acting. For mostnegative-acting photoresists, those coating layer portions that areexposed to activating radiation polymerize or crosslink in a reactionbetween a photoactive compound and polymerizable reagents of thephotoresist composition. Consequently, the exposed coating portions arerendered less soluble in a developer solution than unexposed portions.For a positive-acting photoresist, exposed portions are rendered moresoluble in a developer solution while areas not exposed remaincomparatively less developer soluble. Photoresist compositions aredescribed in Deforest, Photoresist Materials and Processes, McGraw HillBook Company, New York, ch. 2, 1975 and by Moreau, SemiconductorLithography, Principles, Practices and Materials, Plenum Press, NewYork, ch. 2 and 4.

More recently, chemically-amplified-type resists have been increasinglyemployed, particularly for formation of sub-micron images and other highperformance applications. Such photoresists may be negative-acting orpositive-acting and generally include many crosslinking events (in thecase of a negative-acting resist) or deprotection reactions (in the caseof a positive-acting resist) per unit of photogenerated acid. In thecase of positive chemically-amplified resists, certain cationicphotoinitiators have been used to induce cleavage of certain “blocking”groups pendant from a photoresist binder, or cleavage of certain groupsthat comprise a photoresist binder backbone. See, for example, U.S. Pat.Nos. 5,075,199; 4,968,581; 4,883,740; 4,810,613; and 4,491,628, andCanadian Patent Application 2,001,384. Upon cleavage of the blockinggroup through exposure of a coating layer of such a resist, a polarfunctional group is formed, e.g., carboxyl or imide, which results indifferent solubility characteristics in exposed and unexposed areas ofthe resist coating layer. See also R. D. Allen et al., Proceedings ofSPIE, 2724:334-343 (1996); and P. Trefonas et al. Proceedings of the11th International Conference on Photopolymers (Soc. Of PlasticsEngineers), pp 44-58 (Oct. 6, 1997).

While currently available photoresists are suitable for manyapplications, current resists also can exhibit significant shortcomings,particularly in high performance applications such as formations ofhighly resolved sub-half micron and sub-quarter micron features.

Consequently, interest has increased in photoresists that can bephotoimaged with short wavelength radiation, including exposureradiation of about 250 nm or less, or even about 200 nm or less, such aswavelengths of about 248 nm (provided by KrF laser) or 193 nm (providedby an ArF exposure tool). See European Published Application EP915382A2.Use of such short exposure wavelengths can enable formation of smallerfeatures. Accordingly, a photoresist that yields well-resolved imagesupon 248 nm or 193 nm exposure could enable formation of extremely small(e.g. sub-0.25 μm) features that respond to constant industry demandsfor smaller dimension circuit patterns, e.g. to provide greater circuitdensity and enhanced device performance.

However, many current photoresists are generally designed for imaging atrelatively higher wavelengths, such as G-line (436 nm) and I-line (365nm) are generally unsuitable for imaging at short wavelengths such assub-200 nm. Even shorter wavelength resists, such as those effective at248 nm exposures, also are generally unsuitable for sub-200 nmexposures, such as 193 nm imaging.

More specifically, current photoresists can be highly opaque toextremely short exposure wavelengths such as 193 nm, thereby resultingin poorly resolved images.

It thus would be desirable to have new photoresist compositions,particularly resist compositions that can be imaged at short wavelengthssuch as sub-200 nm exposure wavelengths, particularly 193 nm.

SUMMARY OF THE INVENTION

We have now found novel polymers and photoresist compositions thatcomprise the polymers as a resin binder component. The photoresistcompositions of the invention can provide highly resolved relief imagesupon exposure to extremely short wavelengths, particularly sub-200 nmwavelengths such as 193 nm.

Polymers of the invention contain a oxygen- and/or sulfur-containingheteroalicyclic ring that is preferably fused to the polymer backbone(i.e. at least two heteroalicyclic ring atoms as part of the polymerbackbone). The heteroalicyclic ring has one or more oxygen and/or sulfuratoms as ring members.

Preferred polymers of the invention also contain a carbon alicyclicgroup (i.e. the group has all carbon ring members) that is fused to thepolymer backbone, i.e. the carbon alicyclic ring has at least two carbonring members that comprise the polymer backbone. Preferred fused carbonalicyclic groups are provided by polymerization of cyclic olefin(endocyclic double bond) compounds such as optionally substitutednorbornene groups. We have found that incorporation of such carbonalicyclic groups into a polymer can significantly increase plasma etchresistance of a photoresist containing the polymer.

Preferred heteroalicyclic polymer units may be substituted, e.g. byheteroalkyl groups such as ethers (alkoxy) preferably having 1 to about10 carbon atoms, alkylthio preferably having 1 to about 10 carbon atoms,alkylsulfinyl preferably 1 to about 10 carbon atoms, alkylsulfonylpreferably having 1 to about 10 carbon atoms, and the like. It has beensurprising found that such substituents can provide enhancedlithographic results, particularly enhanced substrate adhesion.

For use in photoresist compositions, polymers of the invention also willcontain one or more units that comprise photoacid-labile moieties. Thephotoacid-labile group may be a substituent of one or more of theabove-mentioned units, such as a substituent of a polymerized vinylalicyclic ether, vinyl alicyclic thioether or carbon alicyclic group.The photoacid labile moiety also may be present as an additional polymerunit, e.g. as a polymerized alkyl acrylate or alkylmethacrylate,particularly an acrylate having an alicyclic moiety such asmethyladamantyl acrylate or methyladamantyl methacrylate. Preferredalicyclic photoacid-labile moieties are tertiary ester alicyclichydrocarbon groups that have two or more fused or bridged rings.Preferred tertiary ester groups include optionally substitutedadamantyl, particularly methyl adamantyl as mentioned above; optionallysubstituted fencyl groups, particularly ethyl fencyl; optionallysubstituted pinanyl; and optionally substituted tricyclo decanyl,particularly an alkyl-substituted tricyclo decanyl such as8-ethyl-8-tricyclodecanyl e.g. as provided by polymerization of8-ethyl-8-tricyclodecanyl acrylate and 8-ethyl-8-tricyclodecanylmethacrylate. Additional alicyclic ester groups also will be suitable,including additional bicyclic, tricyclic and other polycyclic moieties.

Polymers of the invention also may contain units in addition to theabove groups. For example, polymers of the invention also may containnitrile units such as provided by polymerization of methacrylonitrileand acrylonitrile. Additional contrast enhancing groups also may bepresent in polymers of the invention, such as groups provided bypolymermization of methacrylic acid, acrylic acid, and such acidsprotected as photoacid labile esters, e.g. as provided by reaction ofethoxyethyl methacrylate, t-butoxy methacrylate, t-butylmethacrylate andthe like.

Generally preferred polymers of the invention contain 3, 4 or 5 distinctrepeat units, i.e. preferred are terpolymers, tetrapolymers andpentapolymers that contain one or more heteroalicyclic groups asdisclosed herein.

Polymers of the invention are preferably employed in photoresists imagedat 193 nm, and thus preferably will be substantially free of any phenylor other aromatic groups. For example, preferred polymers contain lessthan about 5 mole percent aromatic groups, more preferably less thanabout 1 or 2 mole percent aromatic groups, more preferably less thanabout 0.1, 0.02, 0.04 and 0.08 mole percent aromatic groups and stillmore preferably less than about 0.01 mole percent aromatic groups.Particularly preferred polymers are completely free of aromatic groups.Aromatic groups can be highly absorbing of sub-200 nm radiation and thusare undesirable for polymers used in photoresists imaged with such shortwavelength radiation.

The invention also provides methods for forming relief images, includingmethods for forming a highly resolved relief image such as a pattern oflines where each line has essentially vertical sidewalls and a linewidth of about 0.40 microns or less, and even a width of about 0.25,0.20 or 0.16 microns or less. The invention further provides articles ofmanufacture comprising substrates such as a microelectronic wafersubstrate or liquid crystal display or other flat panel displaysubstrate having coated thereon a polymer, photoresist or resist reliefimage of the invention. Other aspects of the invention are disclosedinfra.

DETAILED DESCRIPTION OF THE INVENTION

As discussed above, polymers of the invention contain a heteroalicyclicring that is preferably fused to a polymer backbone. The fusedheterocyclic ring units contain one. or more oxygen and/or sulfur atoms.By stating herein that a cyclic group is fused to a polymer backbone, itis meant that two ring members of the cyclic group, typically twoadjacent carbon atoms of the cyclic group, are also part of the polymerbackbone. Such a fused ring can be provided by polymerizing a cyclicmonomer that has an endocyclic double bond.

Preferred oxygen ring polymer units will be free of other hetero atomssuch as sulfur (i.e. only oxygen and carbon ring members). Typically,the oxygen ring unit will contain a single oxygen ring atom and may haveone or more ring substituents. As discussed above, it has been foundthat such ring substituents can significantly enhance substrateadhesion.

Additionally, an oxygen heteroalicyclic group will be present in apolymer together with polymerized carbon alicyclic compounds such asoptionally substituted norbornene. As referred to herein, the term“carbon alicyclic group” means each ring member of the non-aromaticgroup is carbon. The carbon alicyclic group can have one or moreendocyclic carbon-carbon double bonds, provided the ring is notaromatic.

Preferred polymers of the invention that contain oxygen heteroalicyclicunits comprise a structure of the following Formula I:

wherein X, Y, and each Z are each independently carbon or oxygen, withat least one of X, Y or Z being oxygen, and preferably no more than twoof X, Y and Z being oxygen;

Q represents an optionally substituted carbon alicyclic ring fused tothe polymer backbone (i.e. two Q ring members being adjacent carbons ofthe polymer backbone); the alicyclic ring suitably having from about 5to about 18 carbon atoms and is suitably a single ring (e.g.cyclopentyl, cyclohexyl or cycloheptyl), or more preferably Q ispolycyclic e.g. and contain 2, 3, 4 or more bridged, fused or otherwiselinked rings, and preferred substituents of a substituted Q groupinclude photoacid-labile moieties such as a photoacid-labile ester;

each R is the same or different non-hydrogen substituent such as cyano;optionally substituted alkyl preferably having 1 to about 10 carbonatoms; optionally substituted alkanoyl preferably having 1 to about 10carbon atoms; optionally substituted alkoxy preferably having 1 to about10 carbon atoms; optionally substituted alkylthio preferably having 1 toabout 10 carbon atoms; optionally substituted alkylsulfinyl preferably 1to about 10 carbon atoms; optionally substituted alkylsulfonylpreferably having 1 to about 10 carbon atoms; optionally substitutedcarboxy preferably have 1 to about 10 carbon atoms (which includesgroups such as —COOR′ where R′ is H or C₁₋₈alkyl, including esters thatare substantially non-reactive with photoacid); a photoacid-labile groupsuch as a photoacid-labile ester e.g. a tert-butyl ester and the like;etc.

m is 1 (to provide a fused five-membered ring), 2 (to provide a fusedsix-membered ring), 3 (to provide a fused seven-membered ring), or 4 (toprovide a fused eight-membered ring);

n is an integer of from 0 (i.e. no R ring substituents), 1 (i.e. asingle R ring substituent) to the maximum possible value permitted bythe valences of the ring members, and preferably n is 0, 1, 2, 3, 4 or5, and more preferably n is 0, 1, 2 or 3;

p is the mole fraction of the fused oxygen ring units based on totalunits in the polymer; and r is the mole fraction of the fused carbonalicyclic ring units based on total units in the polymer, and p and rare each greater than zero.

As discussed above, preferred carbon alicyclic ring units arepolymerized optionally substituted norbornene groups. Thus, preferredpolymers that contain oxygen heteroalicyclic units comprise a structureof the following Formula IA:

wherein X, Y, Z, R, m and n are the same specified for Formula I above;

R¹ and R² are each independently hydrogen or a non-hydrogen substituentsuch as halo (F, Cl, Br, I), nitro, cyano, optionally substituted alkyl(including cycloalkyl) preferably having from 1 to about 16 carbons;optionally substituted alkoxy preferably having from 1 to about 16carbons; optionally substituted alkylthio preferably having from 1 toabout 16 carbons; optionally substituted carboxy preferably have 1 toabout 10 carbon atoms (which includes groups such as —COOR′ where R′ isH or C₁₋₈alkyl, including esters that are substantially non-reactivewith photoacid); a lactone; an anhydride such as an itaconic anhydridegroup; a photoacid-labile group such as a photoacid-labile ester,particularly a photoacid-labile ester moiety with a tertiary alicyclicgroup or a non-cyclic group such as t-butyl; and the like, or R′ and R²may be taken together to form one or more rings fused to the depictednorbornyl ring;

p is the mole fraction of the fused oxygen ring units based on totalunits in the polymer; and r is the mole fraction of the fused optionallysubstituted norbornene ring units based on total units in the polymer,and p and r are each greater than zero.

Particularly preferred oxygen ring polymer units include those that havefive or six ring members and an oxygen ring member adjacent to thepolymer backbone. Accordingly, preferred are polymers that comprise astructure of the following Formula IB:

wherein each Z′ is independently oxygen, sulfur or carbon, andpreferably each Z′ is carbon; m′ is 1, 2, 3 or 4; and R and n are eachthe same as defined in Formula I above, and preferably n is 0, 1, 2, 3,4 or 5, and more preferably n is 0, 1, 2 or 3;

Q is the same as defined in Formula I;

p is the mole fraction of the fused oxygen ring units based on totalunits in the polymer; and r is the mole fraction of the fused carbonalicyclic ring units based on total units in the polymer, and p and rare each greater than zero.

Preferred polymers of Formula IB contain polymerized norbornene units,e.g. polymers that comprise a structure of the following Formula IC:

wherein Z′, m′, R, n, and p are the same as defined in Formula IB; and

R¹, R² and r are the same as defined in Formula IA.

Preferred sulfur ring polymer units also will be free of other heteroatoms such as oxygen (i.e. only sulfur and carbon ring members), or willcontain only one or two other hetero atoms such as oxygen, typicallyonly one additional heteroatom such as oxygen.

Preferred sulfur ring polymer units include those of the followingFormula II:

wherein X, Y, and each Z are each independently carbon, oxygen orsulfur, with at least one of X, Y or Z being sulfur, and preferably nomore than two of X, Y and Z being sulfur;

each R is the same or different non-hydrogen substituent such as cyano;optionally substituted alkyl preferably having 1 to about 10 carbonatoms; optionally substituted alkanoyl preferably having 1 to about 10carbon atoms; optionally substituted alkoxy preferably having 1 to about10 carbon atoms; optionally substituted alkylthio preferably having 1 toabout 10 carbon atoms; optionally substituted alkylsulfinyl preferably 1to about 10 carbon atoms; optionally substituted alkylsulfonylpreferably having 1 to about 10 carbon atoms; optionally substitutedcarboxy preferably have 1 to about 10 carbon atoms (which includesgroups such as —COOR′ where R′ is H or C₁₋₈alkyl, including esters thatare substantially non-reactive with photoacid); a photoacid-labile groupsuch as a photoacid-labile ester e.g. a tert-butyl ester and the like;etc.

m is 1 (to provide a fused five-membered ring), 2 (to provide a fusedsix-membered ring), 3 (to provide a fused seven-membered ring) or 4 (toprovide a fused eight-membered ring);

n is an integer of 0 (no R substituents present), 1 (i.e. a single Rring substituent) to the maximum possible substitution permitted by thevalences of the ring members, and preferably n is 0, 1, 2, 3, 4 or 5,and more preferably n is 0, 1, 2 or 3; and

p is greater than zero and is the mole fraction of the fused sulfur ringunits based on total units in the polymer.

Particularly sulfur ring polymer units include those that have five, sixor seven ring members and an sulfur ring member adjacent to the polymerbackbone, such as units of the following Formula IIA:

wherein Y is the same as specified for Formula I above;

wherein each Z′ is independently carbon, oxygen, or sulfur; andpreferably is Z′ is carbon; m′ is 1, 2, 3 or 4; and R and n are each thesame as defined in Formula I above, and preferably n is 0, 1, 2, 3, 4 or5, and more preferably n is 0, 1, 2 or 3; and

p is greater than zero and is the mole fraction of the fused sulfur ringunits based on total units in the polymer.

Polymers of the invention also may contain oxygen or sulfur ring groupsthat are spaced from the polymer backbone. The spaced oxygen or sulfurring group suitably will contain a single ring, although polycyclicrings that contain one or more oxygen or sulfur ring members also willbe suitable. Less preferred are groups where sulfur or oxygen is abridgehead atom of a polycyclic group, particularly a bridgehead of abicyclic group such as a oxonorbornyl or thionorbonyl group, especiallyif such oxonorbornyl or thionorbonyl group is present as part of anester moiety.

For example, suitable spaced oxygen and/or sulfur ring groups of polymerof the invention include those of the following Formula III:

wherein W is a linker; X, Y, and each Z are each independently carbon,oxygen, or sulfur, with at least one of X, Y or Z being oxygen orsulfur;

each R is the same or different non-hydrogen substituent such as thosenon-hydrogen substituents specified for R in Formula I above;

m is 1, 2, 3, 4 or 5; n is an integer of from 0 to the maximum valuesubstitution permitted by the valences of the ring members; and p is themole percent of the units in the polymer.

Typical W linker groups of Formula III include e.g. optionallysubstituted alkylene particularly optionally substituted C₁₋₈ alkylene;optionally substituted alkenylene particularly optionally substitutedC₂₋₈ alkenylene; optionally substituted alkynylene particularlyoptionally substituted C₂₋₈ alkynylene; optionally substitutedheteroalkylene particularly optionally substituted C₁₋₈ heteroalkylene;optionally substituted heteroalkenylene particularly optionallysubstituted C₂₋₈ heteroalkenylene; optionally substitutedheteroalkynylene particularly optionally substituted C₂₋₈heteroalkynylene; an ester linkage (i.e. —C(═O)O); and the like. InFormula III, the spaced oxygen or sulfur ring group may be a componentof a photoacid-labile group, such as a photoacid-labile ester group.Such groups may be provided by polymerization of the correspondingacrylate or methacrylate groups.

Preferably, a sulfur heteroalicyclic group will be present in a polymerwith polymerized carbon alicyclic olefin compounds. More specifically,preferred polymers of the invention include those that comprise astructure of the following Formula IV:

wherein X, Y, Z, R, m, n and p are each the same as defined in FormulaII above;

Q and r are the same as defined for Formula I above.

Preferred carbon alicyclic ring units are polymerized optionallysubstitutednorbornene groups. Thus, preferred polymers that containsulfur heteroalicyclic units comprise a structure of the followingFormula IVA:

wherein X, Y, Z, R, m and n are the same specified for Formula II above;

R¹ and R² are the same as defined in Formula IA above;

p is the mole fraction of the fused sulfur ring units based on totalunits in the polymer; and r is the mole fraction of the fused optionallysubstituted norbornene ring units based on total units in the polymer,and p and r are each greater than zero.

Particularly preferred sulfur ring polymer units include those that havefive, six, seven or eight ring members and a sulfur ring member adjacentto the polymer backbone. Accordingly, preferred are polymers thatcomprise a structure of the following Formula IVB:

wherein each Z′ is independently oxygen, sulfur or carbon, andpreferably is carbon; m′ is 1, 2, 3 or 4; and R and n are each the sameas defined in Formula I above, and preferably n is 0, 1, 2, 3, 4 or 5,and more preferably n is 1, 2 or 3;

Q is the same as defined in Formula I;

p is the mole fraction of the fused sulfur ring units based on totalunits in the polymer; and r is the mole fraction of the fused carbonalicyclic ring units based on total units in the polymer, and p and rare each greater than zero.

Preferred polymers of Formula IVB contain polymerized norbornene units,e.g.polymers that comprise a structure of the following Formula IVC:

wherein Z′, m′, R, n, and p are the same as defined in Formula IVB; and

R¹, R² and r are the same as defined in Formula IA.

In the above Formulae I, IA, IB, IC, II, IIA, III, IV, IVA, IVB and IVC,and the below Formulae V, VI and VII (together sometimes referred toherein simply as “the formulae” or similar phrase), preferably Rsubstituents of the depicted heteroalicyclic unit are electron-donatinggroups such as optionally substituted alkyl, optionally substitutedalkoxy or optionally substituted alkylthio. Such electron-donatinggroups can facilitate polymerization of the corresponding vinylheteroalicyclic monomer.

Preferred polymers of the invention will contain at least about 2 to 5mole percent of fused heteroalicyclic units based on total units of thepolymer; more preferably from about 5 to 50 mole percent of fusedheteroalicyclic units based on total units of the polymer; still morepreferably from about 5 or 10 to about 40 or 50 percent of fusedheteroalicyclic units based on total units of the polymer.

Preferred polymers of the invention will contain at least about 2 to 5mole percent of carbon alicyclic units based on total units of thepolymer; more preferably from about 5 to 50 mole percent of fused carbonalicyclic units based on total units of the polymer; still morepreferably from about 5 or 10 to about 25 or 30 percent of fused carbonalicyclic units based on total units of the polymer.

In polymers of the invention that contain only heteroalicyclic units andcarbon alicyclic units, preferably the heterocyclic units will bepresent in an amount of from about 5 to about 90 or 95 mole percentbased on total polymer units, and the carbon alicyclic units will bepresent in an amount of from about 5 to about 90 or 95 mole percentbased on total polymer units.

In polymers of the invention that consist of heteroalicyclic units,carbon alicyclic units and maleic anhydride units (i.e.heteroalicyclic:carbon alicyclic:maleic anhydride terpolymers),preferably the heterocyclic units will be present in an amount of fromabout 5 to about 10, 20, 30, 40, 50, 60, 70 or 80 mole percent based ontotal polymer units, the carbon alicyclic units (such as optionallysubstituted norbornene) will be present in an amount of from about 5 toabout 10, 20, 30, 40, 50, 60, 70 or 80 mole percent based on totalpolymer units, and the maleic anhydride units will be present from about5 to about 20, 30, 40 or 50 mole percent based on total polymer units;and more preferably the heterocyclic units will be present in an amountof from about 5 to about 10, 20, 30, 40, 50 or 60 mole percent based ontotal polymer units, the carbon alicyclic units will be present in anamount of from about 5 to about 10, 20, 30, 40, 50 or 60 mole percentbased on total polymer units, and the maleic anhydride units will bepresent from about 5 to about 10, 15, 20, 25, 30, 40, or 50 mole percentbased on total polymer units. In such terpolymers, suitably either orboth the heteroalicyclic or carbon alicyclic units will contain aphotoacid labile substituents such as a photoacid-labile estersubstituent.

In the above the above formulae, the R, R¹ and R² substituents each canbe photoacid-labile groups. Photoacid-labile ester groups are generallypreferred such as a tert-butyl ester, or an ester containing a tertiaryalicyclic group. Such photoacid-labile esters may be directly pendantfrom a heteroalicyclic or carbon alicyclic polymer unit (i.e. —C(═O)OR,where R is tert-butyl or other non-cyclic alkyl group, or a tertiaryalicyclic group), or the ester moieties may be spaced from the from aheteroalicyclic or carbon alicyclic polymer unit, e.g. by an optionallyalkylene linkage (e.g. —(CH₂)₁₋₈C(═O)OR, where R is is tert-butyl orother non-cyclic alkyl group, or a tertiary alicyclic group).

In any event, polymers of the invention preferably comprise contain oneor more repeat units that comprise a photoacid-labile group. Asdiscussed with respect to substituents R, R¹ and R² of the aboveformulae, the photoacid-labile may be a substituent of a heteroalicyclicor carbon alicyclic ring member. Alternatively, and generally preferred,the photoacid-labile moiety will be a polymer repeat unit distinct fromrepeat units containing a heteroalicyclic group.

Preferred photoacid-labile groups are ester groups, particularly estersthat contain a tertiary alicyclic hydrocarbon ester moiety. Preferredtertiary alicyclic hydrocarbon ester moieties are polycyclic groups suchadamantyl, ethylfencyl or a tricyclo decanyl moiety. References hereinto a “tertiary alicyclic ester group” or other similar term indicatethat a tertiary alicyclic ring carbon is covalently linked to the esteroxygen, i.e. —C(═O)O—TR′ where T is a tertiary ring carbon of alicyclicgroup R′. In at least many cases, preferably a tertiary ring carbon ofthe alicyclic moiety will be covalently linked to the ester oxygen, suchas exemplified by the below-depicted specifically preferred polymers.However, the tertiary carbon linked to the ester oxygen also can beexocyclic to the alicyclic ring, typically where the alicyclic ring isone of the substituents of the exocyclic tertiary carbon. Typically, thetertiary carbon linked to the ester oxygen will be substituted by thealicyclic ring itself, and/or one, two or three alkyl groups having 1 toabout 12 carbons, more typically 1 to about 8 carbons, even moretypically 1, 2, 3 or 4 carbons. The alicyclic group also preferably willnot contain aromatic substitution. The alicyclic groups may be suitablymonocyclic, or polycyclic, particularly bicyclic or tricyclic groups.

Preferred alicyclic moieties (e.g. group TR′ of —C(═O)O—TR′) ofphotoacid labile ester groups of polymers of the invention have ratherlarge volume. It has been found that such bulky alicyclic groups canprovide enhanced resolution when used in copolymers of the invention.

More particularly, preferred alicyclic groups of photoacid labile estergroups will have a molecular volume of at least about 125 or about 130Å³, more preferably a molecular volume of at least about 135, 140, 150,155, 160, 165, 170, 175, 180, 185, 190, 195, or 200 Å³. Alicyclic groupslarger than about 220 or 250 Å³ may be less preferred, in at least someapplications. References herein to molecular volumes designatevolumetric size as determined by standard computer modeling, whichprovides optimized chemical bond lengths and angles. A preferredcomputer program for determining molecular volume as referred to hereinis Alchemy 2000, available from Tripos. For a further discussion ofcomputer-based determination of molecular size, see T Omote et al,Polymers for Advanced Technologies, volume 4, pp. 277-287.

Particularly preferred tertiary alicyclic groups of photoacid-labileunits include the following, where the wavy line depicts a bond to thecarboxyl oxygen of the ester group, and R is suitably optionallysubstituted alkyl, particularly C₁₋₈ alkyl such as methyl, ethyl, etc.

Polymers of the invention also may contain photoacid-labile groups thatdo not contain an alicyclic moiety. For example, polymers of theinvention may contain photoacid-labile ester units, such as aphotoacid-labile alkyl ester. Generally, the carboxyl oxygen (i.e. thecarboxyl oxygen as underlined as follows: —C(═O)O) of thephotoacid-labile ester will be covalently linked to the quaternarycarbon. Branched photoacid-labile esters are generally preferred such ast-butyl and —C(CH₃)₂CH(CH₃)₂.

Polymers of the invention also may contain additional units such ascyano units, lactone units or anhydride units. For example,acrylonitrile or methacrylonitrile may be polymerized to provide pendantcyano groups, or maleic anhydride may be polymerized to provide a fusedanhydride unit.

Particularly preferred polymers of the invention include those thatcomprise a structure of the following Formula V:

wherein X, Y, Z, R, m and n are each the same as defined in Formula Iabove;

R¹ and R² are each independently hydrogen or a non-hydrogen substituentsuch as specified for R¹ and R² in Formula IA above;

R³ is hydrogen or alkyl, particularly C₁₋₆ alkyl such as methyl;

R⁴ is a group that renders the depicted ester photoacid-labile, such asa tertiary alicyclic group as discussed above, or a branched non-cyclicoptionally substituted alkyl group, with the ester carboxyl group beingdirectly bonded to a quaternary (i.e. no hydrogen substituents) carbonatom; and

a, b, c, and d are each greater than zero and are mole fractions of therespective polymer units.

Preferred polymers of the invention also include those of the followingFormula VI:

wherein X, Y, Z, R, m and n are each the same as defined in Formula IIabove;

R¹ and R² are each independently hydrogen or a non-hydrogen substituentsuch as such as specified for R¹ and R² in Formula IA above;

R³ is hydrogen or alkyl, particularly hydrogen or C₁₋₆ alkyl such asmethyl;

R⁴ is a group that renders the depicted ester photoacid-labile, such asa tertiary alicyclic group as discussed above, or a branched non-cyclicoptionally substituted alkyl group, with the ester carboxyl group beingdirectly bonded to a quaternary (i.e. no hydrogen substituents) carbonatom; and

a, b, c, and d are each greater than zero and are mole fractions of therespective polymer units.

In each of above Formulae V and VI, preferably “a” (mole fraction ofheterocyclic units) is from about 2 to 50 mole percent based on totalpolymer units; more preferably “a” is from about 2 to about 40 molepercent based on total polymer units; and still more preferably “a” isfrom about 2 to about 30 mole percent based on total polymer units.

In each of above Formulae V and VI, preferably “b” (mole fraction ofnorbornene units) is from about 2 to 25 mole percent based on totalpolymer units; more preferably “b” is from about 2 to about 20 molepercent based on total polymer units; and still more preferably “b” isfrom about 2 to about 15 or 20 mole percent based on total polymerunits.

In each of above Formulae V and VI, preferably “c” (mole fraction ofanhydride units) is from about 0 (i.e. no anhydride units) to 50 molepercent based on total polymer units; more preferably “c” is from about2 to about 40 mole percent based on total polymer units.

In each of above Formulae V and VI, preferably “d” (mole fraction ofphotoacid-labile ester unit) is from about 2 to 70 mole percent based ontotal polymer units; more preferably “d” is from about 5 or 10 to about70 mole percent based on total polymer units; still more preferably “d”is from about 5 or 10 to about 50 mole percent based on total polymerunits.

Preferred heteroalicyclic units of Formulae V and VI are the same asdescribed above regarding Formulae IA and IIA respectively.

As discussed above, polymers of the invention are preferably employed inphotoresists imaged at short wavelengths, particularly sub-200 nm suchas 193 nm and 157 nm. Polymers also can be employed in photoresistsimaged at higher wavelengths such as 248 nm. For such higher wavelengthapplications, the polymer may suitably contain aromatic units, e.g.polymerized styrene or hydrostyrene units.

Specifically preferred polymers of the invention include those of thefollowing Formula VII:

In Formula VII above, “Alicyclic LG” is the same as defined foralicyclic substituent R⁴ in Formulae V and VI above and is preferablymethyladamantyl, 8-ethyl-8-tricyclodecanyl, ethylfencyl and the like; R¹is C₁₋₈ alkyl, preferably C₁₋₄ alky, o9r a moietty that forms aphotoacid-labile group; R² is suitably hydrogen or C₁₋₈ alkyl, such asmethyl, ethyl, propyl and the like; R¹ and R² are the same as definedfor R¹ and R² respectively in Formula IA above; and a, b, c and d aremole percents of the specified units in the polymer based on totalpolymer units. Preferably a (mole percent of oxygen alicyclic units) isfrom 1 to about 5, 10, 20, 30, 40, 50 or 60 mole percent; b (molepercent of optionally substituted norbornene units) is from 1 to about5, 10, 20, 30, 40, 50 or 60 mole percent; c (mole percent of maleicanhydride units) is from 1 to about 5, 10, 20, 30, 40, or 50 molepercent. Units d (acrylate photoacid-labile units) may be not be present(i.e. d is zero) where the heterocyclic or norbornene units contain aphotoacid-labile units, or d may be suitably present at from about 2 to10, 20, 30, 40 or 50 mole percent based on total polymer units.

As discussed, various moieties may be optionally substituted, includinggroups of Formulae I, IA, II, IIA, III, IV, IVA, IVB, IVC, V, VI, andVII. A “substituted” substituent may be substituted at one or moreavailable positions, typically 1, 2, or 3 positions by one or moresuitable groups such as e.g. halogen (particularly F, Cl or Br); cyano;C₁₋₈ alkyl; C₁₋₈ alkoxy; C₁₋₈ alkylthio; C₁₋₈ alkylsulfonyl; C₂₋₈alkenyl; C₂₋₈ alkynyl; hydroxyl; nitro; alkanoyl such as a C₁₋₆ alkanoyle.g. acyl and the like; etc.

Preferred alkanoyl groups, including as specified in the above formulae,will have one or more keto groups, such as groups of the formula—C(═O)R″ where R″ is hydrogen or C₁₋₈ alkyl. Suitable lactone groups,including as specified in the above formulae, includealpha-butyrolactone groups and the like.

Polymers of the invention can be prepared by a variety of methods. Onesuitable method is an addition reaction which may include free radicalpolymerization, e.g., by reaction of selected monomers to provide thevarious units as discussed above in the presence of a radical initiatorunder an inert atmosphere (e.g., N₂ or argon) and at elevatedtemperatures such as about 70° C. or greater, although reactiontemperatures may vary depending on the reactivity of the particularreagents employed and the boiling point of the reaction solvent (if asolvent is employed). Suitable reaction solvents include e.g.tetrahydrofaran, ethyl lactate and the like. Suitable reactiontemperatures for any particular system can be readily determinedempirically by those skilled in the art based on the present disclosure.A variety of free radical initiators may be employed. For example, azocompounds may be employed such as azo-bis-2,4-dimethylpentanenitrile.Peroxides, peresters, peracids and persulfates also could be employed.

Other monomers that can be reacted to provide a polymer of the inventioncan be identified by those skilled in the art. For example, to providephotoacid-labile units, suitable monomers include e.g. methacrylate oracrylate that contains the appropriate group substitution (e.g. tertiaryalicyclic, t-butyl, etc.) on the carboxy oxygen of the ester group.Maleic anhydride is a preferred reagent to provide fused anhydridepolymer units. Itaconic anhydride also is a preferred reagent to provideanhydride polymer units, preferably where the itaconic anhydride haspurified such as by extraction with chloroform prior to polymerization.Vinyl lactones are also preferred reagents, such as,alpha-butyrolactone.

Some suitable vinyl (endocyclic double bond) heterocyclic monomers thatcan be polymerized to provide polymers of the invention include thefollowing:

Preferably a polymer of the invention will have a weight averagemolecular weight (Mw) of about 800 or 1,000 to about 100,000, morepreferably about 2,000 to about 30,000, still more preferably from about2,000 to 15,000 or 20,000, with a molecular weight distribution (Mw/Mn)of about 3 or less, more preferably a molecular weight distribution ofabout 2 or less. Molecular weights (either Mw or Mn) of the polymers ofthe invention are suitably determined by gel permeation chromatography.

Polymers of the invention used in photoresist formulations shouldcontain a sufficient amount of photogenerated acid labile ester groupsto enable formation of resist relief images as desired. For instance,suitable amount of such acid labile ester groups will be at least 1 molepercent of total units of the polymer, more preferably about 2 to 50mole percent, still more typically about 3 to 30 or 40 mole percent oftotal polymer units. See the examples which follow for exemplarypreferred polymers.

As discussed above, the polymers of the invention are highly useful as aresin binder component in photoresist compositions, particularlychemically-amplified positive resists. Photoresists of the invention ingeneral comprise a photoactive component and a resin binder componentthat comprises a polymer as described above.

The resin binder component should be used in an amount sufficient torender a coating layer of the resist developable with an aqueousalkaline developer.

The resist compositions of the invention also comprise a photoacidgenerator (i.e. “PAG”) that is suitably employed in an amount sufficientto generate a latent image in a coating layer of the resist uponexposure to activating radiation. Preferred PAGs for imaging at 193 nmand 248 nm imaging include imidosulfonates such as compounds of thefollowing formula:

wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularlyperfluorooctanesulfonate, perfluorononanesulfonate and the like. Aspecifically preferred PAG isN-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.

Sulfonate compounds are also suitable PAGs, particularly sulfonatesalts. Two suitable agents for 193 nm and 248 nm imaging are thefollowing PAGS 1 and 2:

Such sulfonate compounds can be prepared as disclosed in European PatentApplication 96118111.2 (publication number 0783136), which details thesynthesis of above PAG 1.

Also suitable are the above two iodonium compounds complexed with anionsother than the above-depicted camphorsulfonate groups. In particular,preferred anions include those of the formula RSO₃— where R isadamantane, alkyl (e.g. C₁₋₁₂ alkyl) and perfluoroalkyl such asperfluoro (C₁₋₁₂alkyl), particularly perfluorooctanesulfonate,perfluorobutanesulfonate and the like.

Other known PAGS also may be employed in the resists of the invention.Particularly for 193 nm imaging, generally preferred are PAGS that donot contain aromatic groups, such as the above-mentionedimidosulfonates, in order to provide enhanced transparency.

A preferred optional additive of resists of the invention is an addedbase, particularly tetrabutylammonium hydroxide (TBAH), ortetrabutylammonium lactate, which can enhance resolution of a developedresist relief image. For resists imaged at 193 nm, a preferred addedbase is a hindered amine such as diazabicyclo undecene ordiazabicyclononene. The added base is suitably used in relatively smallamounts, e.g. about 0.03 to 5 percent by weight relative to the totalsolids.

Photoresists of the invention also may contain other optional materials.For example, other optional additives include anti-striation agents,plasticizers, speed enhancers, etc. Such optional additives typicallywill be present in minor concentrations in a photoresist compositionexcept for fillers and dyes which may be present in relatively largeconcentrations, e.g., in amounts of from about 5 to 30 percent by weightof the total weight of a resist's dry components.

The resists of the invention can be readily prepared by those skilled inthe art. For example, a photoresist composition of the invention can beprepared by dissolving the components of the photoresist in a suitablesolvent such as, for example, ethyl lactate, ethylene glycol monomethylether, ethylene glycol monomethyl ether acetate, propylene glycolmonomethyl ether; propylene glycol monomethyl ether acetate and3-ethoxyethyl propionate. Typically, the solids content of thecomposition varies between about 5 and 35 percent by weight of the totalweight of the photoresist composition. The resin binder and photoactivecomponents should be present in amounts sufficient to provide a filmcoating layer and formation of good quality latent and relief images.See the examples which follow for exemplary preferred amounts of resistcomponents.

The compositions of the invention are used in accordance with generallyknown procedures. The liquid coating compositions of the invention areapplied to a substrate such as by spinning, dipping, roller coating orother conventional coating technique. When spin coating, the solidscontent of the coating solution can be adjusted to provide a desiredfilm thickness based upon the specific spinning equipment utilized, theviscosity of the solution, the speed of the spinner and the amount oftime allowed for spinning.

The resist compositions of the invention are suitably applied tosubstrates conventionally used in processes involving coating withphotoresists. For example, the composition may be applied over siliconwafers or silicon wafers coated with silicon dioxide for the productionof microprocessors and other integrated circuit components.Aluminum-aluminum oxide, gallium arsenide, ceramic, quartz, copper,glass substrates and the like are also suitably employed.

Following coating of the photoresist onto a surface, it is dried byheating to remove the solvent until preferably the photoresist coatingis tack free. Thereafter, it is imaged through a mask in conventionalmanner. The exposure is sufficient to effectively activate thephotoactive component of the photoresist system to produce a patternedimage in the resist coating layer and, more specifically, the exposureenergy typically ranges from about 1 to 100 mJ/cm², dependent upon theexposure tool and the components of the photoresist composition.

As discussed above, coating layers of the resist compositions of theinvention are preferably photoactivated by a short exposure wavelength,particularly a sub-300 and sub-200 nm exposure wavelength. As discussedabove, 193 nm is a particularly preferred exposure wavelength. 157 nmalso is a preferred exposure wavelength. However, the resistcompositions of the invention also may be suitably imaged at higherwavelengths. For example, a resin of the invention can be formulatedwith an appropriate PAG and sensitizer if needed and imaged at higherwavelengths e.g. 248 nm or 365 nm.

Following exposure, the film layer of the composition is preferablybaked at temperatures ranging from about 70° C. to about 160° C.Thereafter, the film is developed. The exposed resist film is renderedpositive working by employing a polar developer, preferably an aqueousbased developer such as quaternary ammonium hydroxide solutions such asa tetra-alkyl ammonium hydroxide solution; various amine solutionspreferably a 0.26 N tetramethylammonium hydroxide, such as ethyl amine,n-propyl amine, diethyl amine, di-n-propyl amine, triethyl amine, ormethyldiethyl amine; alcohol amines such as diethanol amine ortriethanol amine; cyclic amines such as pyrrole, pyridine, etc. Ingeneral, development is in accordance with procedures recognized in theart.

Following development of the photoresist coating over the substrates thedeveloped substrate may be selectively processed on those areas bared ofresist, for example by chemically etching or plating substrate areasbared of resist in accordance with procedures known in the art. For themanufacture of microelectronic substrates, e.g., the manufacture ofsilicon dioxide wafers, suitable etchants include a gas etchant, e.g. ahalogen plasma etchant such as a chlorine or fluorine-based etchant sucha Cl₂ or CF₄/CHF₃ etchant applied as a plasma stream. After suchprocessing, resist may be removed from the processed substrate usingknown stripping procedures.

All documents mentioned herein are incorporated herein by reference. Thefollowing non-limiting examples are illustrative of the invention.

EXAMPLES 1-2 Polymer Syntheses EXAMPLE 1 Synthesis of Tetrapolymer of:2-(6-Ethoxy)tetrahydropyran:norbornene:maleic anhydride:2-methyladmantyl(Respective Molar Ratio of Units of 10:20:30:40)

A mixture of 2-methyladamantyl methacrylate (60.0 g), maleic anhydride(18.84 g), norbornene (12.03 g), 3,4-dihydro-2-ethoxy-2-H-pyran (8.20 g)and V601 (photoinitiator; 3.73 g; 5 mole % of total monomers) in 99.07 g(1/1=Monomer/solvent) of anhydride inhibitor free tetrahydrofuran wasplaced in a round-bottomed flask. After stirring for 5 minutes (untilall solids were dissolved in the solvent), the flask was put into apre-heated 70° C. oil bath. The reaction mixture was stirred at thattemperature for 24 hours. After cooling, 99.07 g of THF was added to thereaction mixture. The polymer was isolated by precipitation into 2.0 Lof hexane/isopropyl alcohol (1:1 wt. %). The suspension was stirred for120 minutes. Then, the polymer was filtered off, and the filteredpolymer was washed with an additionall 200 mL of hexane. The polymer wasdried in a vacuum oven at 40° C. for overnight (about 16 hours). Yield=76.3%.

EXAMPLE 2 Synthesis of Tetrapolymer of:2-(6-Methoxy)tetrahydropyran:norbornene:maleic anhdride:2-methyladmantyl(Respective Molar Ratio of Units of 10:20:30:40)

The title polymer was prepared by the same general procedures asdisclosed above in Example 1, except 7.31 g of3,4-dihydro-2-methoxy-2-H-pyran was used in place of3,4-dihydro-2-ethoxy-2-H-pyran. Yield of polymer was 78.4%.

EXAMPLES 3-6 Syntheses of Monomers Useful in Preparation of Polymers ofthe Invention EXAMPLE 3 EtTCD Methacrylate Monomer Synthesis

8-ethyl-8-tricyclodecanylmethacrylate (EtTCD methacrylate) was preparedas following using the reagents and amounts thereof as specified in thefollowing table.

Material Amt (g) Amt (ml) Moles Source TCD 150.22 1.00 TCIEthylmagnesiumchloride(25%) 390.85 ˜379.5 ˜1.10 ACROS Methacryloylchloride 120.22 ˜112.4 ˜1.15 Aldrich Tetrahydrofuran 480 540 Aldrich

All reaction glassware was dried in the oven overnight at 100° C. Theglassware was set up and cooled under a stream- of nitrogen. Thereaction was carried out under a blanket of nitrogen.

To a 2L 3N-RB flask fitted with a gas inlet, thermometer, overheadstirrer and a rubber septum was added 400 g of ethylmagnesium chloride,25 wt % solution in tetrahydrofuran (clear, amber solution) via a doubletipped needle using nitrogen pressure. The mixture was cooled to −25 to−30° C. using a dry ice/isopropanol bath. While the ethylmagnesiumchloride solution was cooling the 153.6 g of tricyclodecane (TCD) wasdissolved in 480 g of tetrahydrofuran. To a IL 3N-RB flask equipped witha gas inlet, glass stopper and a rubber septum was added the 153.6 g ofTCD. The anhydrous, inhibitor free tetrahydrofuran was transferred tothe IL flask via a double tipped needle using nitrogen pressure. Whenthe ethylmagnesium chloride was at −25 to −30° C., the TCD/THF solutionwas transferred over a 2 hr period to the 2L 3N-RB flask containing theethylmagnesium chloride via a double tipped needle using nitrogenpressure. The cooling bath was removed and the reaction mixture wasstirred for 2 hr. After stirring for 2 hr the mixture was again cooledto −25 to −30° C. using a dry ice/isopropanol bath. The methacryloylchloride (120.22 g) was, then added dropwise over a 1 hour period usinga 125 ml pressure equalizing dropping funnel. The reaction was allowedto come to room temperature with overnight stirring. A white precipitatedeveloped from the clear amber colored reaction solution. Water (DI) wasadded until all of the salts had dissolved (˜500 ml) and two distinctlayer were seen. The layers were separated and the organic (upper) layerwas washed with 2×400 ml DI water then dried over magnesium sulfate. TheTHF was removed leaving 258 g of an orange oil. The orange oil wasdissolved in 400 g of hexane then passed through a 400 g silica gel plugwhich had been pre-conditioned with hexane. The silica was washed withhexane until all of the product was removed (spot filtrate on a TLCplate and illuminate under short UV). The hexane was removed leaving202.8 g of an clear, colorless oil. Theoretical yield: 248.4 g; yield:81.6%

EXAMPLE 4 Synthesis of Norbornene Valerolactone

A solution of valerolactone (50.1 g) in 150 mL of anhydrous THF wasplaced in a three-neck-bottomed flask at −78° C. (Dry Ice/acetone). Toit, solution of LDA (250 mL, 2M) in 250 mL anhydrous THF was addeddropwise. The reaction mixture was stirred at this temperature for 4hours. Then, the thermal cracking of paraformaldehyde (36.94 g, excess)was bubbled into the reaction mixture. After the paraformaldehyde wasall cracked, the reaction mixture was stirred at the same bath andstirred for overnight. Then, the solvent was removed by rotary pump andthe residue was added 500 mL CH₂Cl₂ and washed with NaHCO₃ (aq, sat.)and water several times (3×500 mL). The combination organic solvent wasdried over MgSO₄ and the solvent was removed by rotary pump. The desiredproduct was distilled under vacuum (135-140° C./8 mmHg) Themethylene-valerolactone was dissolved in dichloromethane and freshlycracked cyclopentadiene was added. The reaction mixture was stirred atroom temperature for 3 hours, then heated to 40° C., and held at 40° C.overnight. The reaction mixture was then slowly cooled to roomtemperature. The methylene chloride was removed under reduced pressure,leaving an oil. The crude oil was then distilled under reduced pressureto afford pure product.

EXAMPLE 5 Synthesis of 8-Methyltricyclodecanyl Methacrylate

A solution of 125 ml of 1.4 M methyl lithium (in ethyl ether)in 100 mlof hexane was decanted into a three neck round-bottom flask at anice-water bath. To it, a solution of 24.00 g oftricyclo[5.2.1.0]decan-8-one in hexane was added dropwise. Afteraddition, the reaction mixture was stirred for 4 hours at 0° C. Then, asolution of 16 ml of methacroyl chloride in 100 ml of hexane was addeddropwise at 0° After addition, the reaction mixture was stirred at thesame bath for overnight (16 hours). After filtering the white salts, theorganic layer was washed with water three times (3×300 ml). Then, thewashed organic layer was dried over anhydrous MgSO₄. The organic solventwas removed by a rotary pump to give the crude title monomer (23.5 g).The monomer was purified by a flash column chromatography (purity >98%,silica gel with hexane). ¹H NMR: 6.05 (1H), 5.50 (1H), 1.95 (3H), 1.65(3H), 2.25-0.85 (14H).

EXAMPLE 6 Synthesis of Pinanyl Methacrylate

Materials used: Amount Charged Moles Source cis-Pinan-2-ol 15.43 g 0.10Fluka Et₃N 12.14 g 0.12 Aldrich, distilled before use Methacryloylchloride 13.07 g 0.125 Aldrich, distilled before use CH₂Cl₂ 230 mLAldrich, dried and distilled

Procedure:

All reaction glassware and needles were dried and flushed with dry N₂before use and the reaction was carried out under nitrogen atmosphere.

1) Into a 500 mL 3-neck round-bottom-flask equipped with an additionfunnel and a magnetic stirrer were added 15.43 g of cis-pinan-2-ol and200 mL of dry CH₂Cl₂ (Stirred over CaH₂ overnight, then distilled andstored over activated molecular sieves). The resulting colorlesssolution was cooled with an ice-water bath.

2) Triethylamine (12.14 g) was added through the addition funnel to thecooled CH₂Cl₂ solution over 10 min. After added, the resulting solutionwas kept in a dry-ice/acetone bath (−67° C.).

3) A CH₂Cl₂ (30 mL) solution of methacryloyl chloride (13.07 g) wasadded dropwisely over 20 min. The resulting orangish suspension wasallowed to warm to room temperature and stirred for 2 h.

4) The chloride salts were filtered off, The filtrate was washed withsaturated Na₂CO₃ solution (2×200 mL), then DI water (3×200 mL), anddried over anhydrous MgSO₄.

5) The slightly yellow CH₂Cl₂ solution was concentrated on a rotaryevaporator (bath temperature kept below 35°) to yield a clear slightlyyellow liquid product. Yield 79%. The product was judged pure by NMR.

EXAMPLE 7 Photoresist Preparation and Lithographic Processing

A photoresist of the invention is prepared by mixing the followingcomponents with amount expressed as weight percents based on totalweight of the resist composition:

Resist components Amount (wt. % based on total solids) Resin binder 28.2Photoacid generator 0.52 Basic additive 0.03 Surfactant 0.03

The resin binder is the polymer of Example 2 above. The photoacidgenerator is triphenylsulfonium triflate. The basic additive istriisopropnaol amine. The surfactant is Silwet (Dow Chemical). Thoseresist components were formulated at 16 wt. % solids in a solvent of2-heptatone.

The formulated resist composition is spin coated onto HMDS vapor primed4 inch silicon wafers and softbaked via a vacuum hotplate at 130° C. for60 seconds. The resist coating layer is exposed through a photomask at193 nm using an ISI microstepper, and then the exposed coating layersare post-exposure baked (PEB) at about 130° C. The coated wafers arethen treated with 0.26N aqueous tetramethylammonium hydroxide solutionto develop the imaged resist layer and provide a relief image.

Highly resolved 0.13 μm equal lines and spaces (1:1) were obtained.

EXAMPLE 8 Comparative Example

A resist formulation was prepared of essentially the same components andamounts thereof as in Example 7 above, but where the polymer (resinbinder) did not contain a polymerized ether, or other heteroalicyclicunit. The resist was processed as described in Example 7. The smallestresolved equal lines and spaces (1:1) that could be obtained were 0.14μm.

EXAMPLE 9 Plasma Etch Tests

Oxide plasma etch rates of polymers of the invention were examined.

A first (comparative) terpolymer was tested for etch rates. Thatterpolymer contained polymerized units of p-hydroxystyrene, styrene andt-butylacrylate in respective molar ratios of 65:20:15.

Three tetrapolymers of the invention (referred to below as Polymers 1, 2and 3 respectively) having the following structure were then tested foretch rates.

In Polymer 1, the molar ratio of polymer units a:b:c:d was 10:20:30:40.

In Polymer 2, the molar ratio of polymer units a:b:c:d was 10:15:25:50.

In Polymer 3, the molar ratio of polymer units a:b:c:d was 10:10:20:60.

Polymer 1 exhibited three percent greater oxide etch rate resistancethan the comparative hydroxystyrene/styrene/t-butylacrylate terpolymer.Polymer 2 exhibited five percent greater oxide etch rate resistance thanthe comparative hydroxystyrene/styrene/t-butylacrylate terpolymer.Polymer 3 exhibited eight percent greater etch rate resistance than thecomparative hydroxystyrene/styrene/t-butylacrylate terpolymer.

The foregoing description of the invention is merely illustrativethereof, and it is understood that variations and modification can bemade without departing from the spirit or scope of the invention as setforth in the following claims.

What is claimed is:
 1. A photoresist composition comprising aphotoactive component and a polymer that comprises i) a heteroalicyclicunit that contains one or more sulfur ring members, and ii) aphotoacid-labile moiety, wherein the polymer further comprises iii) oneor more units selected from the group consisting of carbon alicyclic,lactone and anhydride, the photoacid-labile moiety is a polymer unitseparate from the heteroalicyclic group unit, and the heterocyclic uniti) that contains one or more sulfur ring members is a polymer unitseparate from the one or more units iii) that are selected from thegroup consisting of carbon alicyclic, lactone and anhydride.
 2. Thephotoresist of claim 1 wherein the polymer comprises carbon alicyclicunits.
 3. The photoresist composition of claim 1 wherein the polymercomprises norbornene units.
 4. The photoresist composition of claim 1wherein the polymer comprises lactone units.
 5. The photoresistcomposition of claim 1 wherein the polymer comprises anhydride units. 6.The photoresist composition of claim 1 wherein the polymer is atetrapolymer.
 7. The photoresist of claim 1 wherein the polymer is apentapolymer.
 8. The photoresist composition of claim 1 wherein thepolymer is substantially free of aromatic groups.
 9. The photoresistcomposition of claim 1 wherein the polymer is completely free ofaromatic groups.
 10. An article of manufacture comprising amicroelectronic wafer substrate having coated thereon a photoresistcomposition of claim
 1. 11. An article of manufacture comprisingamicroelectronic wafer substrate having coated thereon a photoresistcomposition of claim
 2. 12. A polymer that comprises i) aheteroalicyclic unit that contains one or more sulfur ring members, andii) a photoacid-labile moiety, wherein the polymer further comprisesiii) one or more units selected from the group consisting of carbonalicyclic, lactone and anhydride, the photoacid-labile moiety is apolymer unit separate from the heteroalicyclic group unit, and theheterocyclic unit i) that contains one or more sulfur ring members is apolymer unit separate from the one or more units iii) that are selectedfrom the group consisting of carbon alicyclic, lactone and anhydride.13. The polymer of claim 12 wherein the polymer is substantially free ofaromatic groups.
 14. A photoresist composition comprising a photoactivecomponent and a polymer that comprises i) a heteroalicyclic group thatcontains one or more sulfur ring members, ii) a photoacid-labile moiety,wherein the polymer comprises units of the following formula:

wherein Y and Z′ are each independently carbon, oxygen or sulfur; m′ is1, 2, 3 or 4; each R is the same or different non-hydrogen substituent;n is an integer of 0 to the maximum value permitted by the valences ofthe ring members; and p is greater than zero and is the mole percent ofthe units in the polymer.
 15. The photoresist composition of claim 14wherein the polymer comprises norbornene units.
 16. The photoresistcomposition of claim 14 wherein the polymer is a tetrapolymer.
 17. Thephotoresist composition of claim 14 wherein the polymer is apentapolymer.
 18. The photoresist composition of claim 14 wherein thepolymer comprises one or more units selected from the group consistingof carbon alicyclic, lactone and anhydride.
 19. The photoresistcomposition of claim 14 wherein the polymer is substantially free ofaromatic groups.
 20. The photoresist composition of claim 14 wherein thepolymer is completely free of aromatic groups.
 21. An article ofmanufacture comprising a microelectronic wafer substrate having coatedthereon a photoresist composition of claim
 14. 22. A positive-actingphotoresist composition comprising a photoactive component and a polymercomprising a photoacid-labile group and a heteroalicyclic ring that isfused to the polymer backbone and a comprises a sulfur ring atom. 23.The photoresist composition of claim 22 wherein the polymer comprisesnorbornene units.
 24. The photoresist composition of claim 22 whereinthe polymer is a tetrapolymer.
 25. The photoresist composition of claim22 wherein the polymer is a pentapolymer.
 26. The photoresistcomposition of claim 22 wherein the polymer comprises one or more unitsselected from the group consisting of carbon alicyclic, lactone andanhydride.
 27. The photoresist composition of claim 22 wherein thepolymer is substantially free of aromatic groups.
 28. The photoresistcomposition of claim 22 wherein the polymer is completely free ofaromatic groups.